OBJECTIVE: The long-range objective of this application is the elucidation of the relationship between nucleic acid single-strand secondary structure and the biological function of that nucleic acid. Such secondary structure is, in the opinion of the Principal Investigator, important in messenger RNA processing, intervening DNA sequences, RNA promoter sites, and replication origins in DNA synthesis. Fine structure mapping of secondary structural features will be perfected in order to test these hypotheses. Model systems include fd viral DNA, SV40 DNA, 16S E. coli ribosomal RNA, and Drosophila melanogaster ribosomal RNA.